52 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
which are new, it seems necessary for the sake of clearness, to use some 
terms that may need definite explanation. 
1. The germinal material in the embryo is supposed to consist of 
individual cells forming, a layer, the germinal epithelium — 'primor¬ 
dial germ cells. 
2. At a given period in the development of the larva, these primor¬ 
dial germ cells begin to multiply and continue to do so during the so 
called period of multiplication. 
3. At the beginning of multiplication these primordial germ cells 
are called primary spermatogones. 
4. After the first division of the primary spermatogone, they are 
called secondary spermatogones. 
5. After a certain number of divisions in the division period they 
are said to enter on a period of growth. In this stage of their history 
the cells are called spermatocytes. 
6. From the beginning to the end of the growth period the cells 
are called primary spermatocytes or spermatocytes first order. 
7. The spermatocytes of the first order divide twice in succession, 
and while thus dividing, they are called secondary spermatocytes or 
spermatocytes second order. 
8. These last two divisions, corresponding to the maturation 
divisions of the ovum are called the maturation divisions of the matura¬ 
tion period. 
9. At the end of the maturation divisions, the cells become sperma¬ 
tids. 
10. The spermatids then develop into the fully formed spermato¬ 
zoa , the final product. 
11. As soon as the primary spermatogone begins to multiply, a 
colony of similar cells results, which is surrounded by a cellular cap¬ 
sule which is called a cyst. 
12. The cells of this cyst undergo marked changes during the 
development of the germ cells into mature spermatozoa. It seems 
desirable to have a name for these different stages. 
New Terms. 
13. I therefore propose: to call (a) a cyst containing sperma¬ 
togones a gonocyst (pi. 12, fig. 9-13); (6) those cysts containing 
spermatocytes, cytocyst (pi. 13, fig. 35-38); (c) those cysts containing 
spermatids and spermatozoa, spermatocyst (pi. 12, fig. 14-23). 
